The objectives of this study are to reconstruct a turbulence model of both the large Eddy simulation (LES) and the Reynolds-averaged Navier–Stokes simulation (RANS) which can predict wind synopsis in various thermally stratified turbulent boundary layers over any obstacles. Hence, the direct numerical simulation (DNS) of various thermally stratified turbulent boundary layers with/without forward-step, two-dimensional block, or two-dimensional hill is carried out in order to obtain detailed turbulent statistics for the construction of a database for the evaluation of a turbulence model. Also, DNS clearly reveals the characteristics of various thermally stratified turbulent boundary layers with/without forward-step, two-dimensional block, or two-dimensional hill. The turbulence models employed in LES and RANS are evaluated using the DNS database we obtained. In the LES, an evaluated turbulence model gives proper predictions, but the quantitative agreement of Reynolds shear stress with DNS results is difficult to predict. On the other hand, the nonlinear eddy diffusivity turbulence models for Reynolds stress and turbulent heat flux are also evaluated using DNS results of various thermally stratified turbulent boundary layers over a forward-step in which the turbulence models are evaluated using an a priori method. Although the evaluated models do not make it easy to properly predict the Reynolds shear stresses in all cases, the turbulent heat fluxes can be qualitatively predicted by the nonlinear eddy diffusivity for a heat turbulence model. Therefore, the turbulence models of LES and RANS should be improved in order to adequately predict various thermally stratified turbulent boundary layers over an obstacle.

References

References
1.
Nagano
,
Y.
, and
Hattori
,
H.
,
2015
, “
Improvement of an LRN Two-Equation Turbulence Model Reflecting Multi-Time Scales
,”
Int. J. Heat Fluid Flow
,
51
, pp.
221
228
.
2.
Inagaki
,
M.
,
Hattori
,
H.
, and
Nagano
,
Y.
,
2012
, “
A Mixed-Timescale SGS Model for Thermal Field at Various Prandtl Numbers
,”
Int. J. Heat Fluid Flow
,
34
, pp.
47
61
.
3.
Hattori
,
H.
,
Morita
,
A.
, and
Nagano
,
Y.
,
2006
, “
Nonlinear Eddy Diffusivity Models Reflecting Buoyancy Effect for Wall-Shear Flows and Heat Transfer
,”
Int. J. Heat Fluid Flow
,
27
(
4
), pp.
671
683
.
4.
Hunt
,
J. C. R.
, and
Snyder
,
W. H.
,
1980
, “
Experiments on Stably and Neutrally Stratified Flow Over a Model Three-Dimensional Hill
,”
J. Fluid Mech.
,
96
(
4
), pp.
671
704
.
5.
Snyder
,
W. H.
,
Thompson
,
R. S.
,
Eskridge
,
R. E.
,
Lawson
,
R. E.
,
Castro
, I
. P.
,
Lee
,
J. T.
,
Hunt
,
J. C. R.
, and
Ogawa
,
Y.
,
1985
, “
The Structure of Strongly Stratified Flow Over Hills: Dividing-Streamline Concept
,”
J. Fluid Mech.
,
152
(
3
), pp.
249
288
.
6.
Ohya
,
Y.
,
2001
, “
Wind-Tunnel Study of Atmospheric Stable Boundary Layers Over a Rough Surface
,”
Boundary-Layer Meteorol.
,
98
(
1
), pp.
57
82
.
7.
Hattori
,
H.
,
Houra
,
T.
, and
Nagano
,
Y.
,
2007
, “
Direct Numerical Simulation of Stable and Unstable Turbulent Thermal Boundary Layers
,”
Int. J. Heat Fluid Flow
,
28
(
6
), pp.
1262
1271
.
8.
Hattori
,
H.
, and
Nagano
,
Y.
,
2010
, “
Investigation of Turbulent Boundary Layer Over Forward-Facing Step Via Direct Numerical Simulation
,”
Int. J. Heat Fluid Flow
,
31
(
3
), pp.
284
294
.
9.
Hattori
,
H.
, and
Nagano
,
Y.
,
2012
, “
Structures and Mechanism of Heat Transfer Phenomena in Turbulent Boundary Layer With Separation and Reattachment Via DNS
,”
Int. J. Heat Fluid Flow
,
37
, pp.
81
92
.
10.
Hattori
,
H.
,
Umehara
,
T.
, and
Nagano
,
Y.
,
2013
, “
Comparative Study of DNS, LES and Hybrid LES/RANS of Turbulent Boundary Layer With Heat Transfer Over 2D Hill
,”
Flow, Turbul. Combust.
,
90
(
3
), pp.
491
510
.
11.
Hattori
,
H.
, and
Nagano
,
Y.
,
2004
, “
Nonlinear Two-Equation Model Taking Into Account the Wall-Limiting Behavior and Redistribution of Stress Components
,”
Theor. Comput. Fluid Dyn.
,
17
(
5
), pp.
313
330
.
12.
Fadlun
,
E. A.
,
Verzicco
,
R.
,
Orlandi
,
P.
, and
Mohd-Yusofz
,
J.
,
2000
, “
Combined Immersed-Boundary Finite-Difference Methods for Three Dimensional Complex Flow Simulations
,”
J. Comput. Phys.
,
161
(
1
), pp.
35
60
.
13.
Hattori
,
H.
,
Hotta
,
K.
, and
Houra
,
T.
,
2014
, “
Characteristics and Structures in Thermally-Stratified Turbulent Boundary Layer With Counter Diffusion Gradient Phenomenon
,”
Int. J. Heat Fluid Flow
,
49
, pp.
53
61
.
14.
Inagaki
,
M.
,
Kondoh
,
T.
, and
Nagano
,
Y.
,
2005
, “
A Mixed-Time-Scale SGS Model With Fixed Model-Parameters for Practical LES
,”
ASME J. Fluids Eng.
,
127
(
1
), pp.
1
13
.
15.
Smagorinsky
,
J.
,
1963
, “
General Circulation Experiments With the Primitive Equations
,”
Mon. Weather Rev.
,
91
(
3
), pp.
99
164
.
16.
Abe
,
K.
,
Kondoh
,
T.
, and
Nagano
,
Y.
,
1995
, “
A New Turbulence Model for Predicting Fluid Flow and Heat Transfer in Separating and Reattaching Flows—II. Thermal Field Calculations
,”
Int. J. Heat Mass Transfer
,
38
(
8
), pp.
1467
1481
.
17.
So
,
R. M. C.
,
Vimala
,
P.
,
Jin
,
L. H.
,
Zhao
,
C. Y.
, and
Gatski
,
T. B.
,
2002
, “
Accounting for Buoyancy Effects in the Explicit Algebraic Stress Model: Homogeneous Turbulent Shear Flows
,”
Theor. Comput. Fluid Dyn.
,
15
(
5
), pp.
283
302
.
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